Photographic emulsion layers or other hydrophilic colloid layers of silver halide photographic materials are often colored to absorb light in a specific wavelength region.
When the spectral composition of light incident upon a photographic emulsion layer must be controlled, a colored layer is usually provided on a side which is farther away from the support than the photographic emulsion layer. Such a colored layer is called a filter layer. When two or more emulsion layers are provided, a filter layer is sometimes provided therebetween.
On other hand, a colored layer called an antihalation layer is provided between the support and the photographic emulsion layer or on the side of the support opposite to the photographic emulsion layer to prevent blurring of an image, namely, to prevent halation caused by light scattering during or after the passage of light through the photographic emulsion layer. Particularly, light is reflected at the interface between the emulsion layer and the support or at the surface side of the support opposite the emulsion layer of the light-sensitive material, to again enter the photographic emulsion layer. When two or more photographic emulsion layers are provided, the antihalation layer is sometimes interposed therebetween.
Furthermore, the photographic emulsion layer is often colored to prevent reduced sharpness of the image due to scattering of light in the photographic emulsion layer. This phenomenon is generally called irradiation.
Generally, dyes are contained in the hydrophilic colloid layers to be colored. The dyes necessarily meet the following requirements.
(1) The dyes have an appropriate spectral absorption depending on the intended use.
(2) The dyes are photochemically inert. Namely, the dyes do not adversely effect the performance of silver halide photographic emulsion layers in a chemical sense. For example, the dyes do not cause a reduction in sensitivity, latent image fading or fogging.
(3) The dyes are decolorized during the course of photographic processing or (dissolved out) eluted in processing solutions or rinsing water so that any harmful coloration does not remain in the photographic materials after processing.
(4) The dyes do not diffuse from dyed layers into other layers.
(5) The dyes have excellent stability in solution or when introduced into a photographic material, and are neither discolored nor faded upon storage.
When the colored layer is a filter layer or when the colored layer is an antihalation layer provided on the photographic emulsion layer side of the support, the layer is often required to be selectively colored so that other layers are substantially not affected by the coloration. Otherwise, such coloration has an adverse spectral effect on adjacent layers, while the effect of the colored layer as the filter layer or the antihalation layer is reduced. However, when the dye-containing layer and another hydrophilic colloid layer in a wet state are brought into contact with each other, a portion of the dye is often diffused from the former into the latter. Many investigators have hitherto sought to develop techniques to prevent the dye from diffusing into an adjacent layer.
For example, U.S. Pat. Nos. 2,548,564 and 3,625,694 propose a method wherein a hydrophilic polymer having a charge opposite to that of a dissociated anionic dye as a mordant is present with the dye in the same layer, and the dye is localized in a specific layer by interaction with the mordant.
In the dye fixing-decolorizing method using such a mordant, however, a large amount of the mordant must be used in comparison with the amount of the anionic dye. As a result, the thickness of the colored layer is inevitably increased. For example, when the colored layer is used as a filter layer for photographing materials, an increase in the thickness of the layer deteriorates the sharpness of the resulting image. Further, in a system using the mordant, the mordant necessarily does not interfere with the decolorization of sensitizing dyes used in the silver halide emulsions, in addition to the fixation-decolorization of the colored dye. However, the decolorizing performance thereof does not always reach a level which satisfies recent demands for higher image quality and rapid processing of the photographic materials.
Methods for dyeing a specific layer using a water-insoluble dye solid are disclosed in JP-A-56-12639 (the term "JP-A" as used herein means an "unexamined published Japanese patent application"), JP-A-55-155350, JP-A-55-155351, JP-A-63-27838, JP-A-63-197943, European Patents 15,601, 274,723, 276,566 and 299,436, U.S. Pat. No. 4,803,150 and WO 88/04794.
Furthermore, methods for dyeing a specific layer by using fine metal salt particles having a dye adsorbed thereon are disclosed in U.S. Pat. Nos. 2,719,088, 2,496,841 and 2,496,843 and JP-A-60-45237.
Such dyeing methods as described above provide excellent fixation and decolorization capability, but the absorption range thereof is generally broad. The broad absorption range is undesirable when the dyes are used as filter dyes for light in a specific wavelength region.
Furthermore, methods wherein oil-soluble dyes are dispersed with high-boiling organic solvents are disclosed in JP-A-61-204630, JP-A-61-205934, JP-A-62-32460, JP-A-62-56958, JP-A-62-92949, JP-A-62-222248, JP-A-63-40143, JP-A-63-184749 and JP-A-63-316852.
However, when such high-boiling organic solvents are used, the colored layer is softened and the mechanical strength of the layer is lowered. Hence, a larger amount of gelatin must be used, and the use of the high-boiling organic solvents adversely increases the thickness of the layer.
JP-B-51-39853 (the term "JP-B" as used herein means an "examined Japanese patent publication"), JP-A-51-59943, JP-A-53-137131, JP-A-54-32552, JP-A-54-107941, JP-A-56-126830, JP-A-58-149038, U.S. Pat. Nos. 4,199,363, 4,203,716 and 4,990,435 disclose a method wherein a solution of a hydrophobic material such as a dye in an organic solvent is added to an aqueous dispersion of a polymer (polymer latex) to thereby impregnate the polymer latex with the hydrophobic material, thus forming a hydrophobic material-filled polymer latex. The method avoids the problems caused by the above noted high-boiling organic solvents, but the polymer latex particles are unstable during impregnation and tend to become agglomerated. The method is disadvantageous in that a large amount of the polymer must be used to sufficiently impregnate the polymer with the hydrophobic material, removal of a water-soluble organic co-solvent used for impregnation requires much time, and the entire process is lengthy and complicated.